The Screening Core (SC) is a key component of the Antiviral Drug Discovery and Development Center, contributing to the goals of each ofthe individual projects. Through prior NIH funded programs the SC has a legacy set of hits from chemically diverse compound libraries that have not proceeded beyond the screening stage for each Research Team to asses immediately for their mechanism of action. Secondly, the SC will conduct high throughput screening campaigns of -160,000 never before screened compounds for each research project to provide novel hits as reasonable starting points for the Research Teams and Medicinal Chemistry and Lead development Core (MCLDC). These hits will be analyzed to define their mechanism of action by the Research Teams. Replication inhibitors from either the current or previous screening efforts will funnel into a MCLDC chemistry program designed to optimize their efficacy and selectivity. The SC will also assist the Research Teams and the MCLDC by providing screening data to support the structure activity relationship (SAR) projects to further the CETR's goal of developing new replication inhibitor therapeutics for the treatment of emerging pathogens. Having a core with medium throughput capacity is essential to meet the goal of having leads with the appropriate characteristics to enter animal studies within five years. The resulting data about these compounds, generated by the SC and Research Projects, will be maintained in a centralized database with easy access by the members of the project teams. The SC will incorporate key members ofthe MCLDC and Research Project teams into the screening and decision making procedures. The end result of this process will be the identification of novel compounds appropriate for IND enabling studies.